How the heck are these grades calculated?
How can I get the workshop to switch phase automatically?
In Settings > Workshop Administration > Edit settings tick the box 'Switch to the next phase after the submissions deadline' in the access control section. The workshop will then automatically switch to the assessment phase - after the next time cron is run on your Moodle. (Depending on your Moodle administration, you might be able to run it manually by typing into your browser YOURMOODLE.com/admin/cron.php (where YOURMOODLE.com is the name of your Moodle site).
How can I make reviewing anonymous?
If you do not want your students to know whose work they are reviewing and who is reviewing their work, go to Settings>Workshop administration>Permissions and click the X next to student to prevent "view author names" mod/workshop:viewauthornames and "view reviewer names" mod/workshop:viewreviewernames
Can I use Workshop for students to peer assess an offline activity?
You can, although they will have to submit something, even though that might be a blank document. See this forum post for more information: https://moodle.org/mod/forum/discuss.php?d=220054#p958145